OPA186: Can OPA186 support common voltage input 25V with 23V supply?

Hi Marsh,

Marsh Cai said:

1, Can OPA186 support common voltage input 25V with 23V supply? According to the D/S, the max input = VCC+0.5.

OPA186 is unable to support the linear operation of 25V input with 23Vdc supply rail. The image below refers to the absolute maximum rating without damaging the op amp. 

The marked box in red is the linear operation of Vcm input range in OPA186.  

Marsh Cai said:

2, Do we have products support 25V input with 23V power supply?

Can you tell me about the application? If you are able to provide us with more application details, I can provide you with a simulation for the requirements. 

The op amps that will operate linearly with input voltage greater than the supply voltage are likely difference amplifiers, such as INA592, INA597 etc., see the link below (The input front ends have voltage dividers to accommodate for the input  Vcm signal greater than the supply voltage). 

https://www.ti.com/amplifier-circuit/difference/products.html?keyMatch=DIFFERENCE%20AMPLIFIER#p480=1&sort=p358max;desc

If you have additional questions, please let us know. 

Best,

Raymond

HI Raymond,

It will be used as the buffer for driving ADC.

Do you have any proposals?

BRs,

Marsh

Hi Marsh, 

Marsh Cai said:

It will be used as the buffer for driving ADC.

Using OPA186 as buffer to drive ADC, I do not have a good recommendation. Options are:

1. increase the supply rails from 23Vdc to 26Vdc or higher range. 

2. Divide down the input signal by 1/2 or similar and gains up later and take into account of ADC sampling. This is no difference from using a difference amplifier, except using difference amplifier may have better CMRR and accuracy. 

3. Improve the output driving signal's driving capability, and to eliminate the buffer (but I need to know what types of input signal (25Vdc) are). 

Please provide us with more information, maybe we can recommend other alternatives.

Best,

Raymond